Method for drilling holes in soil or rock material and for fixing an anchor in a borehole and apparatus therefor

ABSTRACT

For drilling holes in soil or rock material and for fixing an anchor in a borehole, an expanding element fixed to a drill or anchor rod and a spreading element are introduced with the rod into the soil or rock material, the spreading element is expanded to butt against the wall of the borehole after completion thereof by the rod. The expanding element being retracted into the spreading element. The rod is secured by an anchor plate on an outer side of the borehole. After expansion of the spreading element, the rod is subjected to a rotary movement in the direction of the interior of the borehole until there is abutment with the interior of the borehole. The rod is fixed to the outside of the borehole by bracing the anchor plate by means of a nut.

The present invention relates to a method for drilling holes in soil or rock material and for fixing an anchor in a borehole, wherein an expanding element fixed to a drill or anchor rod and a spreading element to be expanded, in particular in the form of a sleeve, are introduced with the drill or anchor rod provided with a drill bit, into the soil or rock material at the same time as the borehole is being formed, in particular by rotary and percussive or rotary drilling, the spreading element is expanded to butt against the wall of the borehole after completion of the borehole by the drill or anchor rod and the expanding element arranged thereon being retracted into the interior of the spreading element, and the drill or anchor rod is secured at its end protruding from the borehole by an anchor plate on an outer side of the borehole, and apparatus for drilling holes in soil or rock material and for fixing an anchor in a borehole, including a drill bit fixed to a drill or anchor rod and an expanding element fixed to the drill or anchor rod and an expandable spreading element, in particular in the form of a sleeve, wherein an anchor plate is arranged on the drill or anchor rod, in the end region facing the outside of the borehole.

In the context of mounting or fixing an anchor equipped with a spreading element in a borehole, it is known to introduce such an anchor with at least one expandable element arranged on its periphery in the front end region either into a previously completed borehole or at the same time as the borehole is being formed, in order to subsequently provide the fixation of the anchor, in particular spreading anchor, within the borehole and the abutment of the expandable element on the borehole wall by the expansion of the expandable element. After such a provisional mounting or fixation of the anchor on the borehole wall, the introduced anchor frequently is permanently fixed in the borehole by subsequently introducing a curable suspension such as grout.

In doing so, the anchorage or expansion of the spreading element is achieved, as is for instance described in AT-409785, by retracting the spreading element fixed to an anchor rod or by retracting an expanding element into a spreading sleeve, whereupon the spreading sleeve is brought into abutment on the borehole wall. In both cases, it is necessary for the completion of the borehole to cut off the anchor rod length that protrudes from the borehole following such retraction, and to subsequently attach an anchor plate to the free end of the drill or anchor rod and brace the same in a separate operation, wherein it is either possible to further fix the anchor by introducing a curable suspension, or the anchorage formed by spreading the spreading element into the interior of the mountain or expanding the expanding element onto the borehole wall is completed.

Such a mode of operation, on the one hand, involves time-consuming operating steps and, on the other hand, requires all the elements forming an anchorage to be completed to be attached or hinged to the respective device, and brought into the positions intended for their final purposes of use, each after having finished a preceding operating step. Such a mode of operation, in addition to being time-consuming, is also cost-intensive and, in particular, considerable drill rod lengths are, moreover, discarded by sawing to ultimately required lengths, thus not only causing a decrease in the overall length of the anchorage but also requiring a plurality of additional, non-automated operating steps.

The present invention aims to provide a method for drilling holes in soil or rock material and for fixing an anchor in a borehole, and apparatus therefor, which enable positioning in a single operating step of all the elements required for a permanent anchorage and, moreover, allow the entire length of an introduced drill or anchor rod to be used for anchoring so as to provide an anchorage with enhanced reliability as compared to conventional anchorages.

To solve this object, the method according to the invention is characterized in that, after the expansion of the spreading element, the drill or anchor rod is subjected to a rotary movement in the direction of the interior of the borehole until there is abutment with the interior of the borehole, and that the drill or anchor rod is fixed to the outside of the borehole by bracing the anchor plate by means of a nut formed as a locating element for an insertion device. In that the drill or anchor rod, after the expansion of the spreading element, is subjected to a rotary movement in the direction of the interior of the borehole until abutting the interior of the borehole, it has, on the one hand, become possible to provide or utilize the entire length of the anchor rod for an anchorage and, on the other hand, become superfluous to cut the length of the end of the anchor rod protruding from the borehole, thus avoiding considerable weakening of the whole anchorage system. In that, furthermore, the drill or anchor rod is fixed to the outside of the borehole by bracing the anchor plate by means of a nut formed as a locating element for an insertion device, in particular during the reintroduction of the anchor rod into the borehole, it has become possible to position all elements required for the formation of a permanent anchorage in a single operation, such a mode of operation allowing for not only a substantial gain in time by the automation of the process, but, in particular, also the achievement of a significantly safer anchorage by avoiding the temporary detachment and/or subsequent mounting of individual elements.

In order to enable the drill or anchor rod to be safely reintroduced into the interior of the borehole after the expansion of the spreading element, in particular without unfastening the anchorage from the wall of the borehole, the method according to the invention is further developed such that the drill or anchor rod is introduced into the interior of the borehole after the expansion of the spreading element by acting on a shear pin fixed to the drill or anchor rod or passing therethrough and protruding into a recess of the expanding element until it breaks. Following the expansion of the spreading element by retracting the drill or anchor rod and introducing the expanding element into the spreading element, the drill or anchor rod is maintained in the interior of the expanding element by a radial compressive stress utilized by the spreading element, so that, at a new attempt to rotate the drill rod, such movement will be substantially more difficult to perform than the original rotary and/or percussive movement of the drill or anchor rod for the formation of the borehole. Such radial clamping of the drill or anchor rod and the forced setting in motion of the drill or anchor rod causes a shear pin fixed to the drill or anchor rod or passing therethrough and protruding into a recess of the expanding element to be stressed until it breaks such that, after the shear pin has broken off, a rotary movement of the anchor rod out of the expanding element in the direction towards the interior of the borehole will be enabled, thus bringing the drill rod into abutment on the interior of the borehole by a new rotary movement. During such a mode of operation, the expanding element itself is stationarily maintained by the radial compressive stress of the spreading element and, optionally, a sleeve provided therefor.

In order to safely ensure the breaking of the shear pin, the method according to the invention, according to a further development, is conducted such that the drill or anchor rod, which is designed as a threaded rod, is merely subjected to a rotary movement to act upon the shear pin. Such a mode of operation ensures that the expanding element will not be inadvertently driven out of the interior of the spreading element by a possibly excessive percussive stress, which would render the anchorage loose and/or useless.

In that, as in correspondence with a further development of the method according to the invention, the anchor plate is braced against the outside of the borehole by subjecting the nut fixed to the drill or anchor rod by means of an internal thread merely to a rotary movement, it has additionally and, in particular, simultaneously become feasible by the merely rotating action on the drill or anchor rod for introducing the latter into the interior of the borehole after the expansion of the spreading element to brace the anchor plate arranged on the drill or anchor rod and fixed to the anchor rod by a nut having an internal thread. Such a mode of operation thus not only renders superfluous the cutting to length of the anchor rod, but also enables the introduction and mounting of any elements required for fixing an anchor in soil or rock material in a single operation step.

In order to safely maintain within the borehole also a curable material to be introduced into the interior of the borehole and ensure a material bond with the anchor rod and the borehole, the method, as in correspondence with a further development of the method according to the invention, is conducted such that a borehole cover fitted to the anchor plate in the direction of the interior of the borehole for sealing the borehole against the outside is introduced into the borehole at the same time as the anchor plate is being braced.

To solve the initially mentioned objects, an apparatus for drilling holes in soil or rock material and for fixing an anchor in a borehole is essentially characterized in that the drill or anchor rod is configured as a threaded rod capable of being subjected to a rotary movement after the expansion of the spreading element, said threaded rod cooperating with an internal thread of the expanding element. In that the expanding element is formed with at least one recess in its end region facing the interior of the borehole, which recess cooperates with at least one shear pin engaging said recess and protruding beyond the outer contour of the drill or anchor rod, it has become feasible to make even more reliable the movement of retraction of the drill or anchor rod and the new driving of the latter into the interior of the borehole, since any inadvertent displacement of the expanding element on the drill rod will be safely prevented. When reintroducing the drill or anchor rod into the interior of the borehole, it is, moreover, possible to merely introduce the drill rod into said interior by simply turning off the shear pin, and the expanding element will be held in a secure bond with the spreading element so as to ensure the anchorage of the anchor to the borehole wall.

In that, as in correspondence with a further development of the invention, the expanding element is formed with at least one recess in its end region facing the interior of the borehole, which recess cooperates with at least one shear pin engaging said recess and protruding beyond the outer contour of the drill or anchor rod, it has become feasible to safely pull back, or carry along, the expanding element into the interior of the spreading element during the retraction of the drill or anchor rod.

In that, as in correspondence with a further development of the invention, the thread of the expanding element extends over a portion of the length of the expanding element, it has, in particular, become feasible to keep the wedge-likely tapering parts of the expanding element thread-free, and hence avoid further unnecessary weakening of the same, yet provide a safe retention of the expanding element on the anchor rod.

According to a further development of the invention, a particularly simple expansion of the spreading element will be enabled in that the spreading element is designed as a spring cage comprising a slot extending at least over a portion of its length. Such a device, on the one hand, ensures the safe retention of the spreading element on the anchor rod and, on the other hand, ensures the reliable spreading of the same against the wall of the borehole. Such a spring cage can be designed either with a smooth outer contour or with a teethed outer contour in the manner of a “dowel”.

In that, as in correspondence with a further development of the method according to the invention, the drill or anchor rod interacts with the insertion device for the drill or anchor rod via a nut for fixing the anchor plate, it has become feasible, on the one hand, to introduce any parts required for the formation of an anchorage in a single operating step and, on the other hand, to achieve a minimization of the elements required for the setting of an anchor. By such a configuration it has, furthermore, become possible to arbitrarily subject the nut to a rotary movement via the internal thread on the anchor rod designed as a threaded rod and hence, for instance, fix the anchor plate to the exterior of the borehole, and, by the insertion device engaging the external thread, to safely and reliably introduce the whole device into the interior of the borehole and retract the same by the distance required for spreading the spreading element, and subsequently drive it in again.

In order to achieve, in particular, the automated insertion of a drill or anchor rod and introduce all elements required for the formation of an anchorage in a single operation, a substantially frustoconical borehole cover abutting the anchor plate is arranged on the drill or anchor rod according to a further development of the invention.

In order to ensure the reliable expansion of the spreading element, the device according to the invention is further developed to the effect that, in a manner known per se, a stop sleeve crimped to the drill or anchor rod is provided on the drill or anchor rod for the spreading element. Such a device ensures the reliable spreading of the spreading element and hence the safe abutment on the inner wall of the borehole.

In the following, the invention will be explained in more detail by way of exemplary embodiments illustrated in the drawing. Therein:

FIG. 1 depicts an apparatus according to the invention for forming a borehole and for fixing drill or anchor rods in the interior of the formed borehole;

FIG. 2 is a top view of a modified variant of the apparatus according to FIG. 1;

FIG. 3 is a partially sectioned, schematic view of the apparatus of FIG. 2 in a state fixed to the wall of the borehole; and

FIG. 4 depicts an enlarged sectional view of the borehole cover.

In FIG. 1, a drill or anchor rod is denoted by 1, to whose end facing a borehole interior 15 a drill bit 2 is fixed in a non-extendible manner. The drill or anchor rod 1, over its entire length, is designed as a threaded rod, on which an expanding element 3 is mounted in such a manner that the recesses 4 formed within the expanding element 3 overlap a shear pin 5 protruding beyond an outer periphery of the drill or anchor rod 1. The expanding element 3 in its inner periphery, which is not apparent from the drawing, can be wholly or partially formed with a thread cooperating with the thread 6 of the drill or anchor rod 1. Such a configuration ensures the captive maintenance of the expanding element 3 in its selected position and, in particular, prevents the shear pin 5 from being inadvertently torn off.

A spreading element 7, which is provided with a longitudinal slot 8 over a portion of its length, is maintained on the drill or anchor rod 1 at a distance from the expanding element 3 by a sleeve 9 crimped to the drill or anchor rod 1. The spreading element 7 is configured such that the longitudinal slot 8 merely extends over a portion of the length of the spreading element 7, and that the part of the spreading element 7 facing the wall of the borehole is designed with kind of a teething 10. The teething 10 is provided for a better engagement in the borehole wall.

The drill rod 1, on its end region facing the exterior of the borehole, is provided with a cover element 11 for the borehole, an anchor plate 12 butting against the cover element 11, and a nut 13 provided as a locating element for a schematically indicated insertion device 14. The cover element 11 in this case is formed as a cone that tapers towards the interior of the borehole to safely and reliably seal the formed borehole. The anchor plate 12 may be a conventional anchor plate 12, which, for instance, is brought into abutment on a tunnel wall by exerting an external compressive stress.

The nut 13, which is designed as a location element for the insertion device 14, can be formed as a nut 13 with both an internal thread and an external thread so as to be safely and reliable guided on the anchor rod 1, on the one hand, and ensure the safe engagement of the insertion device 14 on the outer surface of the nut 13.

In the illustration according to FIG. 2, the reference numerals of FIG. 1 have been retained as far as possible. The configuration according to FIG. 2 differs from that of FIG. 1 merely in that the spreading element 7 is designed as a spring sleeve formed with a continuous slot 8. Apart from that the spreading element 7 designed as a spring sleeve has no other pattern or contouring on its outer periphery.

In the illustration according to FIG. 3, which depicts the device according to FIG. 2 in a state braced within the borehole interior 15 and held in abutment on the borehole wall, the reference numerals of FIG. 1 and FIG. 2 have again been retained. From the illustration according to FIG. 3, it is apparent that the drill bit 2 contacts the borehole interior 15 after the retraction of the expanding element 3 into the spreading element 7 and reintroduction into the borehole. To this end, the drill or anchor rod 1 was retracted into the interior of the spreading element 7 along with the drill bit 2 and the expanding element 3 in a first step, while an axial displacement in the direction to the outside of the borehole of the spreading element 7 was prevented by the provision of the sleeve 9 crimped to the anchor rod 1. The introduction of the expanding element 3 causes the spreading element 7 to expand until butting against the borehole wall, which is schematically indicated by 16. After the expansion operation has been completed, the drill rod assembly 1 is again urged in the direction of the borehole interior 15 by a further movement, in particular rotary movement, exerted by the insertion device 14 (not illustrated) engaging the nut 13. During such a rotary movement, twisting of the expanding element 3 in the interior of the spreading element 7 is prevented by the forces acting on the expanding element 3 in the radial direction, of the spreading element 7, and the rotary movement of the drill bit 1 merely causes the shear pin 5, which is no longer visible in FIG. 3, to tear off so as to enable the drill rod 1 to freely rotate in the interior of the expanding element 3. The rotary movement of the drill rod 1 is continued until the drill bit 2 is in abutment on the borehole wall 15. While the drill rod 1 is again driven into the borehole interior 15, the anchor plate 12 and the cover element 11 are acted upon at the same time as the nut 13, thus causing the two elements to close the formed borehole from outside. Such a device thus, on the one hand, enables the drill or anchor rod 1 to be introduced into the borehole over the entire length of the formed borehole so as to safely prevent the protrusion of an end of the anchor rod 1 from the formed borehole and, on the other hand, allows any operating steps necessary for the formation of a borehole and the fixation of an anchorage in the borehole to be performed in a single operation.

FIG. 4 depicts a partially perspective, sectional view of an optional variant of a borehole cover 11. The borehole cover 11 in this case is mounted on the drill or anchor rod 1 for rotary movement via internal threads 17 and, due to the conical configuration of the borehole cover 11, has a diameter increasing in the direction towards the outside of the borehole. Such a device not only enables the formation of a borehole, but also safeguards the latter against any inadvertent penetration of material, or the inadvertent penetration of curable material to be optionally introduced simultaneously with the formation of the anchorage, such as grout. 

1. A method for drilling holes in soil or rock material and for fixing an anchor in a borehole, wherein an expanding element fixed to a drill or anchor rod and a spreading element to be expanded, in particular in the form of a sleeve, are introduced with the drill or anchor rod provided with a drill bit, into the soil or rock material at the same time as the borehole is being formed, in particular by rotary and percussive or rotary drilling, the spreading element is expanded to butt against the wall of the borehole after completion of the borehole by the drill or anchor rod and the expanding element arranged thereon being retracted into the interior of the spreading element, and the drill or anchor rod is secured at its end protruding from the borehole by an anchor plate on an outer side of the borehole, wherein, after the expansion of the spreading element, the drill or anchor rod is subjected to a rotary movement in the direction of the interior of the borehole until there is abutment with the interior of the borehole, and that the drill or anchor rod is fixed to the outside of the borehole by bracing the anchor plate by means of a nut formed as a locating element for an insertion device.
 2. The method according to claim 1, wherein the drill or anchor rod is introduced into the interior of the borehole after the expansion of the spreading element by acting on a shear pin fixed to the drill or anchor rod or passing therethrough and protruding into a recess of the expanding element until it breaks.
 3. The method according to claim 1, wherein the drill or anchor rod, which is designed as a threaded rod, is merely subjected to a rotary movement to act upon the shear pin.
 4. The method according to claim 1, wherein the anchor plate is braced against the outside of the borehole by subjecting the nut fixed to the drill or anchor rod by means of an internal thread merely to a rotary movement.
 5. The method according to claim 1, wherein a borehole cover fitted to the anchor plate in the direction of the interior of the borehole for sealing the borehole against the outside is introduced into the borehole at the same time as the anchor plate is being braced.
 6. An apparatus for drilling holes in soil or rock material and for fixing an anchor in a borehole, including a drill bit fixed to a drill or anchor rod and an expanding element fixed to the drill or anchor rod and a spreading element, in particular in the form of a sleeve, which is arranged at a distance from the expanding element and at least partially surrounds the drill or anchor rod, said expanding element being expandable to butt against the wall of the borehole by the retraction of the drill or anchor rod, wherein an anchor plate is arranged on the drill or anchor rod, in the end region facing the outside of the borehole, wherein the drill or anchor rod is configured as a threaded rod capable of being subjected to a rotary movement after the expansion of the spreading element, said threaded rod cooperating with an internal thread of the expanding element, and that the drill or anchor rod interacts with an insertion device via a nut for bracing the anchor plate.
 7. The device according to claim 6, wherein the expanding element is formed with at least one recess in its end region facing the interior of the borehole, which recess cooperates with at least one shear pin engaging said recess and protruding beyond the outer contour of the drill or anchor rod.
 8. The device according to claim 6, wherein the thread of the expanding element extends over a portion of the length of the expanding element.
 9. The device according to claim 6, wherein the spreading element is designed as a spring cage comprising a slot extending at least over a portion of its length.
 10. The device according to claim 6, wherein the nut has an internal thread and an external thread.
 11. The device according to claim 6, wherein a substantially frustoconical borehole cover abutting the anchor plate is arranged on the drill or anchor rod.
 12. The device according to claim 6, wherein, in a manner known per se, a stop sleeve crimped to the drill or anchor rod is provided on the drill or anchor rod for the spreading element.
 13. (canceled) 